As the size of the device continues to be shrunk, the number of devices per unit area of a chip becomes continuously larger, which leads to an increase of dynamic power consumption. Meanwhile, the continuous shrinking of the size of the device leads to an increase in leakage current, which in turn increases static power consumption. When the semiconductor device is integrated at a high level and channel lengths of MOSFETs becomes shorter continuously, a series of effects which may be neglected in a long-channel model for a MOSFET becomes more significant, and even becomes a dominant factor affecting performance of a device. Such a phenomenon is generally called a short-channel effect. The short-channel effect would deteriorate electronic performance of a device, such as leading to a decrease of the threshold voltage of the gate, an increase of the power consumption a decrease of signal-to-noise ratio, and the like.
An SOI substrate is a substrate in which a silicon dioxide layer is embedded below the silicon. As compared to a bulk silicon device, the device formed by an SOI substrate may obviously reduce leakage current and power consumption to suppress the short channel effect, so such a device has a significant advantage. However, the cost for an SOI substrate is higher and it needs a larger device area to avoid a floating body effect, so it is difficult to meet the requirements of high integration of the device. In addition, since a silicon dioxide layer is embedded, heat dissipation performance is affected.